The first animals ever intentionally sent into space were fruit flies launched aboard a V2 rocket in 1947. US scientists were studying the effects of radiation at high altitude.
Though. The first animal to actually go into orbit was the dog Laika, launched on board the Soviet Sputnik 2 spacecraft on November 3, 1957. Unfortunately, Laika died during the flight.

OMMA rhesus monkey called Albert 1 became the first monkey launched into space on June 11, 1948; also on board a US-launched V2 rocket. These were just suborbital flights, though. The first animal to actually go into orbit was the dog Laika, launched on board the Soviet Sputnik 2 spacecraft on November 3, 1957